1. Field of the Invention
The present invention relates to a temperature control method in image forming apparatuses, such as copying machines, and laser printers.
2. Description of the Related Art
Heretofore, in the image forming apparatuses, temperature rise suppression control has been implemented not to give rise to image defects due to temperature elevation, in other words, to form good images on a recording medium even if the interior temperature rises during an image forming operation. For example, as discussed in Japanese Patent Application Laid-Open No. 6-194921, a control system is installed to control the apparatus to temporarily stop the image forming operation when the internal temperature reaches a predetermined temperature level, and a cooling operation takes place to reduce the temperature in the apparatus, and after the temperature is cooled to some extent, the image forming operation is resumed.
However, when the image forming operation is stopped temporarily for the purpose of cooling, a drop in throughput accrues. In this respect, Japanese Patent Application Laid-Open No. 2005-156758 proposes an image forming apparatus configured such that when a temperature reaches a level at which the image forming operation is to be changed, cooling is performed in such a manner that the image forming time will be as short as possible on the basis of a number of images yet to be printed and a temperature change rate based on the apparatus's interior temperature detected at that time.
In this conventional technology, however, in the control method that changes the operation to another stage after a fixed temperature for a change of operation is reached, no consideration has been given to controlling the image forming operation until the temperature rises to a level for a change of operation. In other words, if the image forming operation can be controlled before the interior temperature rises to the level for a change of operation, it is possible to shorten the image forming time more than when controlling the image forming operation after the interior temperature has reached the level for operation change. There is also a room for improvement in control of the image forming operation at a stage before the temperature rises to a level for a change of operation.